a
Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
E-mail:honglizhao@ecust.edu.cn, minbolan@ecust.edu.cnFax: +86-21-64252947 Tel: +86-21-64253574

b
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China

Abstract

In this work, we fabricated a yolk–shell magnetic composite that contains mesoporous TiO2 as the inner shell and flowerlike NiO as the outer shell (denoted as Fe3O4@H-TiO2@f-NiO) to reduce the limitations of single-component metal oxides in phosphopeptide enrichment. The NiO nanosheets play a synergistic role in phosphopeptide enrichment. And the unique flowerlike structure of NiO with sufficient space can facilitate the reversible insertion/extraction of peptides, which will have less impact on the enrichment process of the inner TiO2 shell. The yolk–shell structure and two types of porous nanostructures endowed this composite with a high surface area (156.58 m2 g−1) and a large pore volume (0.37 cm3 g−1). Owing to the high surface area and combined properties of TiO2 and NiO, the Fe3O4@H-TiO2@f-NiO microspheres showed a better performance for phosphopeptide enrichment than the same material without NiO nanosheets (Fe3O4@H-TiO2). According to the LC-MS/MS results, 972 unique phosphopeptides were identified from HeLa cell extracts with a high selectivity (91.9%) by Fe3O4@H-TiO2@f-NiO relative to 837 phosphopeptides (selectivity: 60.2%) by Fe3O4@H-TiO2. The results demonstrated that, compared with single-component metal oxides, composite metal oxides could enhance the selectivity and sensitivity for phosphopeptide enrichment.

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